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CATEGORIES:Department of Earth Sciences Seminars (downtown)
SUMMARY:Silica enrichment (and depletion) in the cratonic 
 lithosphere - Emma Tomlinson\, Trinity College Dub
 lin
DTSTART;TZID=Europe/London:20250520T120000
DTEND;TZID=Europe/London:20250520T130000
UID:TALK224737AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/224737
DESCRIPTION:It is well established that the cratonic lithosphe
 ric mantle formed as a residue of extensive mantle
  melting during the Archaean. However\, an unexpec
 ted feature of peridotite xenoliths from the crato
 nic lithosphere is that they exhibit silica conten
 ts that extend both above and below that expected 
 after simple peridotite melting\, implying a role 
 for open system processes. High-silica peridotites
 \, rich in orthopyroxene\, are commonly found in t
 he Kaapvaal and Siberian cratons\, whereas low-sil
 ica samples\, such as those from parts of Greenlan
 d and Tanzania contain anomalously high olivine. K
 omatiites are produced by advanced peridotite melt
 ing and predominantly erupted during the Archean\,
  observations that appear to compliment the highly
  refractory nature of Archean peridotites. However
 \, a simple melt-residue relationship is undermine
 d by observations that both komatiite and cratonic
  peridotite have depleted initial Hf-isotope compo
 sitions. Using insights from petrology\, thermodyn
 amic modelling\, geochemistry and high pressure ex
 periments\, this talk will investigate the conditi
 ons of silica enrichment and discuss a potential r
 ole for komatiite-peridotite interaction.
LOCATION:Department of Earth Sciences\, Tilley Lecture Thea
 tre
CONTACT:Dr Rachael Rhodes
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